Law establishes a framework for making decisions about withholding and withdrawing life-sustaining treatment from adults who lack capacity. However, to what extent do doctors know and follow this law? This article reports on a three-year empirical study that sought to answer these questions. The research found that doctors have significant legal knowledge gaps in this area. It also found that doctors do not attach significant weight to legal considerations in their decision-making. This article argues that law does have a role to play in end-of-life care. However, law reform is needed to make the law more accessible, medical education needs to be improved, and a change in attitude by doctors to medical law is required.